Possible to detect if SWF is accessed directly

I have a movie that receives some FlashVars. It isn’t an option to use another method besides FlashVars, but the weakness of this way of working is that someone can just look at the HTML and use the path to the SWF + the FlashVars to open it directly into the browser.

I want to make sure this isn’t possible because this way the user can very easily change the FlashVars and alter the way the movie works.

Is there a way to make sure the SWF can only be opened when it’s loaded from within the HTML document?